Gringo are you just using dry raw plant in your flask? If so, you will burn the plant and get nothing. Secondly, alkaloids are naturally present as polyhydrates of weak acids (or something like that..) and as such, steam will not liberate them, and they get 'trapped' in the plant fibres. You need to add alot of NaOH solution to make the alkaloids freebases, so that when the steam is bubbled through, it will grab the fb-goodies; and u will have a lot more fun.
Also what plant are u using because some plant alkaloids will be visible as a separate oily layer, others (eg freebase pseduo, eph etc from ephedra) are not. I repeat, you will not have a big fat oil layer when distilling ephedra alkaloids (you may see a few light droplets at the most). That said, they are still present and a spaced out throughout the entire distillate (so u cant just remove the top layer to isolate). Meth freebase on the other hand, is nice and fat and imiscible with water.
And yes, 1) superheating the steam and 2) heating the flask contents to near boiling (~95`C) and 3) cool water circulated through your condenser are almost essential to success.